Spectrophotometric determination of benzocaine as an azo dye with acetyl acetone

Abstract

This paper concerned with development of a spectrophotometric method for the
determination of trace amounts of Benzocaine, based on the diazotisation and coupling
reaction with acetyl acetone in basic medium, to form an intense yellow coloured, watersoluble
and stable azo-dye which shows a maximum absorption at 419.5nm. Beer s law is
obeyed over the concentration range of 0.04-12 μg/ml, with molar absorptivity of 25000
l.mol-1.cm-1 and Sandell s sensitivity index of 6.6×10-3μg.cm-2, relative error of -3.80 to
+3.95% and relative standard deviation of ± 0.013to ±0.32%. The method has been
applied successfully for the determination of benzocaine in two synthetic pharmaceutical
formulation.